Part I. Psen LatreilleCONTENTSIntroduction................... ι Systematics................... 3Morphology.................. 4Key to the genera................. 7Psen Latreille.................. 7Key to the subgenera of Psen Latreille........... 8Subgenus Pseneo Malloch.............. 9Subgenus Psen s. str................ 12Key to the Indonesian and Philippine species of the subgenus Psen Latr. 14 Subgenus Mimumesa Malloch............. 50Key to the Indonesian and Philippine species of the subgenus Mimumesa Malloch.................. 52Doubtful species of Psen.............. 56Some Pseninae from the Asiatic continent and Ceylon....... 57Distribution and relationships.............. 62Biological notes.................. 67Literature................... 67Index .................... 69INTRODUCTIONIn this paper an attempt is made to give a review of the Pseninae occurring in that part of the Malay Archipelago which is formed by the Indonesian Islands and the Philippines. In the first place it is based on the collections of the Rijksmuseum van Natuurlijke Historie at Leiden, Netherlands, and